jrgpots Posted March 5, 2014 Report Share Posted March 5, 2014 About 2 months ago I made a terra sig from local clay. It's a magnesium and iron rich bentonite. In its raw state it is purple and chocolate brown in oxidation. I don't know what it looks like in reduction yet. It melt at cone 4-5. I did triaxial blending of Gerstley borate, Nepheline syenite, and the clay with the results below. The glaze has a satin finish with two coats and semi gloss finish with one coat. It has a pleasing texture. I like the tile that has the hole in the test tube. Lemon juice test showed no discolorations. There is no crazing. Recipe: Gerstley bborate 6.52 Neph syenite 15.22 local clay/bentonite 78.26 It was applied on bone dry clay and single -fired to reduce problems with the high bentonite and its COE. I think I have my first stable home grown base glaze. What colorants do you think I should try next? I have thought about adding RIO 6 - 8% to see if it will make a nice satin tenmuko that I could use as the base glase for a cone 6 oil spot or hares hair glaze. That is my aspiration. Imput, critique, gut reactions are greatly appreciated. Jed Link to comment Share on other sites More sharing options...
C. Banks Posted March 5, 2014 Report Share Posted March 5, 2014 we fire to ^8-9 but maybe I can offer a couple starting points 80 local clay 15 local calcium (whiting) 5 rio 2 light mgco3 it had an annoying tendency to blister - nothing serious just the odd 3 or 4 blisters every load. it was tolerable but annoying. I spent some time trying to puzzle them away but gave up after finally figuring out a decent jasper. there is another black recipe I can share with certainty but unfortunately I'm away from my little black book atm and can't remember the jasper exactly. Link to comment Share on other sites More sharing options...
jrgpots Posted March 5, 2014 Author Report Share Posted March 5, 2014 Send it to me if you find it. Thanks Link to comment Share on other sites More sharing options...
C. Banks Posted March 5, 2014 Report Share Posted March 5, 2014 80 local clay 15 whiting 2 coco3 4 rutile this matte gold-black came fully functional with next to no fiddling necessary all amounts are grams Link to comment Share on other sites More sharing options...
C. Banks Posted March 5, 2014 Report Share Posted March 5, 2014 when I get back home in a couple weeks I'll post the jasper Link to comment Share on other sites More sharing options...
C. Banks Posted March 5, 2014 Report Share Posted March 5, 2014 the jasper has 10 grams bone ash, black iron oxide, whiting and I pretty sure 10 grams gb as well. the other couple ingredients im unsure of and it adds up to 114 or something your 'clay' test results sound very familiar the purplish oil spotting I remember with 10+% of rio was encouraging but I got sidetracked after findings spots of red. iirc 12% rio was the most I tried. Link to comment Share on other sites More sharing options...
Wyndham Posted March 5, 2014 Report Share Posted March 5, 2014 You might consider 2 glazes, the one you have as the base with more iron 5%, the other the base plus 3134 frit in increments of 10% with about 4-5% rutile for a breaking gloss over the base Wyndham Link to comment Share on other sites More sharing options...
jrgpots Posted March 5, 2014 Author Report Share Posted March 5, 2014 You might consider 2 glazes, the one you have as the base with more iron 5%, the other the base plus 3134 frit in increments of 10% with about 4-5% rutile for a breaking gloss over the base Wyndham That sounds interesting. I'll be making more test tiles. Jed Link to comment Share on other sites More sharing options...
smastca Posted March 7, 2014 Report Share Posted March 7, 2014 This is my native clay - a red terra cotta. Recipe - terra cotta 80; Frit 3134 20. You can see the little tea dust crystals. Link to comment Share on other sites More sharing options...
TJR Posted March 7, 2014 Report Share Posted March 7, 2014 This is my native clay - a red terra cotta. Recipe - terra cotta 80; Frit 3134 20. You can see the little tea dust crystals. Wow! That's beautiful. Crazing quite a bit though. You could try a line blend of flint-5%.10%15%. To see if you can get a better fit. Of course the frit is also a glass former. TJR. Link to comment Share on other sites More sharing options...
C. Banks Posted April 10, 2014 Report Share Posted April 10, 2014 here is that jasper local clay 50 volcanic ash 10 bone ash 10 silica 10 gerstley borate 10 black iron oxide 10 spodumene 10 kona f4 4 mgco3 3 all in grams nice red breaking black with touches of purple at ^8.5-9 in oxidation Link to comment Share on other sites More sharing options...
TJR Posted April 10, 2014 Report Share Posted April 10, 2014 O.K. I had to rewrite your formula so that it looks more like a percentage local clay 50 volc. ash 10 Flint/silica 10 Ger. Bor. 10 Spodumene10 Total ---------100 Kona f4 4 Mang. carb 3 Black Iron 10 So looking at the percentage now, you still have Kona F4 which is a Soda flux. I left it out of the 100% total just for ease of reading the recipe. If you look at your manganese-you have 3% in the glaze. You also have a huge amount of black iron. I would try a line blend without either the manganese or the iron to see what your base looks like. Then you can add 1% iron, then 2, then 4% etc. If you were firing in reduction, your glaze would be really dark, and probably run. Remember, test,test,test, and show us the results. TJR. Link to comment Share on other sites More sharing options...
C. Banks Posted June 13, 2014 Report Share Posted June 13, 2014 thanks TJR im online very infrequently and wanted to respond here a few times but this phone tech is ... alien this is one of my success stories - it only took a few years but after giving up for a year or so I had a thought and threw a hail mary of sorts the recipe should read magnesium carbonate rather than manganese and is definitely approaching what I would call iron saturated? it is well behaved at ^9 and, when happy, shows no off browns and much maroon/purple character if I was to submit a glaze to cm this would be the first one of ? 3 Link to comment Share on other sites More sharing options...
C. Banks Posted June 13, 2014 Report Share Posted June 13, 2014 this may be a fotm (flavour of the month) but it's fun to share an "ooo" moment Link to comment Share on other sites More sharing options...
jrgpots Posted June 13, 2014 Author Report Share Posted June 13, 2014 Do you have a pic for your latest tweek in the recipe? I'd love to see it. Jed Link to comment Share on other sites More sharing options...
C. Banks Posted June 14, 2014 Report Share Posted June 14, 2014 It might take a while but I have some images and a few pieces saved that shine up well Link to comment Share on other sites More sharing options...
C.Banks Posted February 15, 2015 Report Share Posted February 15, 2015 Do you have a pic for your latest tweek in the recipe? I'd love to see it. Jed I get to live near potter types for the next bit so I thought I'd dig this old thread up with a picture. Hopefully I can sneak a test or three into a few different kilns/atmospheres. I miss testing glaze ideas. Link to comment Share on other sites More sharing options...
oldlady Posted February 16, 2015 Report Share Posted February 16, 2015 that is beautiful. not my thing but i would like it on someone else's work. Link to comment Share on other sites More sharing options...
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